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Contains:  NGC 2244, Rosette nebula, NGC 2239, The star 12Mon
Getting plate-solving status, please wait...
Rosette Nebula, 


            Stephen Migol
Rosette Nebula

Technical card

Imaging telescope or lens:Stellarvue SV4

Imaging camera:Pentax K10D

Mount:Losmandy G11 Gemini II

Guiding telescope or lens:Stellarvue SV 70 ED

Guiding camera:Orion SSAG

Software:Stark Labs DSLR ShutterPixInsightAdobe Lightroom 3Maxim DL

Filter:IDAS LPS-P2

Resolution: 3645x2283

Dates:Nov. 26, 2012

Frames: 28x600"

Integration: 4.7 hours

Avg. Moon age: 12.88 days

Avg. Moon phase: 96.03% job: 105428

RA center: 97.905 degrees

DEC center: 4.986 degrees

Pixel scale: 1.909 arcsec/pixel

Orientation: 91.420 degrees

Field radius: 1.140 degrees

Locations: Menlo Park, Menlo Park, California, United States


Rosette Nebula as seen on Nov 25 and 26 over two nights of capturing in the back yard. I was testing flexure fixes and needed a target that would be useful. This object is near the equator and thus any issues with RA would show up best here.

Equipment used for this effort:
Stellarvue SV4
Full spectrum modified Pentax K10D camera with cooler (Camera temps ranged from 6 to 9 C)
SSF6 flattener with IDAS LPR filter
Losmandy G11 with Gemini 2 and PEC turned on
Guided with Maxim and SSAG on SV70ED

Data set:
32 lights, 45 darks, 256 bias, 35 flats

I've also learned a few new things about the peculairities of the image data I capture. Because I'm using a cooled, full spectrum converted CCD based DSLR, the noise profile is a bit strange. There is amp glow that is non-linear. So far, I've learned that Maxim DL is the best tool for me to use to calibrate the source files. This does a nice job of removing the amp glow, although sometimes it does not do a great job on the hot pixels. It gets nearly all of them, but the biggest ones still come through.

I've been stacking the FIT files from Maxim using Deep Sky Stacker 3.3.3 beta 47. It does a great job of catching the hot pixels and does the right job of debayering the FIT files. I've recently found that my color settings for the debayer process were off by a large margin. I found that by reducing the blue level significantly and bumping up the red level the resulting cyan colored ringing on the brightest stars all but disappears. This has significantly helped the next step of processing in Pix Insight.

Stacked in DSS with Sigma Clip settings of Kappa 2 with 5 iterations on the best 90% giving 28 lights. This gives 4 hours and 40 minutes of integration time. Exported as 32 bit FIT file.

In PI, now that the data is in much better condition, I've had better results with using the basic tools. In order, I run:
Dynamic Crop to trim bad areas from the mosaic from DSS
Assisted Color Calibration
DBE with large sample areas
Masked Stretch script to get to a higher median level
Removed green using SCNR
Histogram Stretch to spread out the results
ADCNR with the built-in masking (I've tried using it twice with good results)
Unsharp Mask on the Luminance CIE Y to tighten up the stars
One more pass on the Assisted Color Calibration with a strong saturation boost value of 3
Dark Structure Enhance script did a nice job of increasing the contrast

Final export to TIFF and then into LR3. There I added a value of 1 to the blacks and 10 to the Clarity, Vibrance, and Saturation each. In the past, I've done Sharpness and Noise Reduction. I don't think this is necessary for this example. I also touched up a spot left from a missing set of flats - I missed getting flats after the first day's data and there was a big dust mote on the CCD.

Here's the platesolve output from PI:

Referentiation Matrix (Gnomonic projection = Matrix * Coords[x,y]):
-0.000012772342 +0.000530587853 -0.582410522327
-0.000530583963 -0.000012822386 +0.981665095443
+0.000000000000 +0.000000000000 +1.000000000000
Resolution ........ 1.911 arcsec/pix
Rotation .......... -88.619 deg
Focal ............. 655.28 mm
Pixel size ........ 6.07 um
Field of view ..... 1d 56' 4.4" x 1d 12' 42.0"
Image center ...... RA: 06 31 37.009 Dec: +04 59 06.77
Image bounds:
top-left ....... RA: 06 29 16.500 Dec: +05 57 59.17
top-right ...... RA: 06 29 05.715 Dec: +04 01 57.74
bottom-left .... RA: 06 34 08.743 Dec: +05 56 13.63
bottom-right ... RA: 06 33 57.099 Dec: +04 00 12.52

All in all, I'm happy with this image. The data is reasonably good and I've learned a lot.



Stephen Migol
License: None (All rights reserved)

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Rosette Nebula, 


            Stephen Migol